The model is R 85i-0. After the model number is XXXXX string of letters and numbers:
REU - V2532FFU - US
You can not, there is no adjustment for that it comes set from the factory already set, you can only adjust the water temperature .
Initial Settings ONLY IF YOU HAVE THE deluxe CONTOL PANEL-When you press the ‘Water Smart / Bath Fill’ button, a Shower /Bath Volume will appear on the indicator. When a deluxe bathroomcontroller(s) is first turned on, So when you press the Water smart bath fill button you can tell the heater to turn on automatically this way you can use the water at a low flow and the heater will turn on. IF you do not have the deluxe controller you can have your current controller fitted. The model number you gave me told me that they are sold with the standard controller which does not have this feature.
Q - When I was using the hot water, the water got cold!A - If you adjusted the flow from the tap to lessen it, you may have gone below the minimumflow required. The Rinnai Water Heater requires a minimum flow rate to operate). If you mix the water with a tap and attempt to get a temperature well below the temperature being controlled by the unit, it may drop the flow below the desired minimum flow rate. Decrease the temperature supplied by the Rinnai Water Heater at the remote control or increase your total flow. Your unit says that it must have 0.6 gallons a minute flowing threw it en order to turn on.
Even if you install different aerators with a higher flow rate, you said that you only have this problem when you only turn the sink on a little , even with new aerators if you still only turn the sink on a Little bit it still will not be enough water flow and you The heater will still not turn on.
Plumbers Protect the Nations Health, , If you aren't 100% satisfied with my Answer, I would be happy to clarify for you. When you feel I have Answered your Question to the best of my ability, please click, (Accept) or you won’t be able to leave me customer feedback and I won't receive credit for Answering this question